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/*!
\file lib/cairodriver/write_ppm.c
\brief GRASS cairo display driver - write PPM image (lower level functions)
(C) 2007-2008 by Lars Ahlzen and the GRASS Development Team
This program is free software under the GNU General Public License
(>=v2). Read the file COPYING that comes with GRASS for details.
\author Lars Ahlzen <lars ahlzen.com> (original contributor)
\author Glynn Clements
*/
#include <grass/glocale.h>
#include "cairodriver.h"
void cairo_write_ppm(void)
{
char *mask_name = G_store(ca.file_name);
FILE *output, *mask;
int x, y;
output = fopen(ca.file_name, "wb");
if (!output)
G_fatal_error(_("Cairo: unable to open output file <%s>"),
ca.file_name);
mask_name[strlen(mask_name) - 2] = 'g';
mask = fopen(mask_name, "wb");
if (!mask)
G_fatal_error(_("Cairo: unable to open mask file <%s>"), mask_name);
G_free(mask_name);
fprintf(output, "P6\n%d %d\n255\n", ca.width, ca.height);
fprintf(mask, "P5\n%d %d\n255\n", ca.width, ca.height);
for (y = 0; y < ca.height; y++) {
const unsigned int *row =
(const unsigned int *)(ca.grid + y * ca.stride);
for (x = 0; x < ca.width; x++) {
unsigned int c = row[x];
int a = (c >> 24) & 0xFF;
int r = (c >> 16) & 0xFF;
int g = (c >> 8) & 0xFF;
int b = (c >> 0) & 0xFF;
if (a > 0 && a < 0xFF) {
r = r * 0xFF / a;
g = g * 0xFF / a;
b = b * 0xFF / a;
}
fputc((unsigned char)r, output);
fputc((unsigned char)g, output);
fputc((unsigned char)b, output);
fputc((unsigned char)a, mask);
}
}
fclose(output);
fclose(mask);
}
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